Safety switch



Feb. l0, 1925. 1,525,474

E, H. THOMPSON SAFETY SWITCH Filed May 20. 1922 Patented Feb. 10, 1925.

UNITED STATES ERNEST H. THOIPSON, 0F EVANHION, ILLINOIS.

SAFETY SWITCH.

Application led Hay 20, 1922. Serial N0. 582,277.

T a all whom it may concern:

Be it known that I, ERNEST H. THOMP- soN, a citizen of the United States, and resident of Evanston, in the county of Cook and State of Illinois, havel invented certain new and useful Improvements in Safety Switches, of which the following is a speciication.

This invention relates to electric snap switches such as are placed on the wall or or other convenient locality adjacent to a door-way in a closet or stairway where it is desired to turn on and turn off the switch which controls the lighting when one enters or leaves the room or passage.

It is a matter of very frequent occurrence that when the light switch has been turned on the one leaving the room will forget to turn off the switch, and as this oversight is induced by reason of the door being closed the lights in that circuit may continue to function for many hours or days in some cases without discovery.

The present invention is intended to prevent any such accidental occurrence by so combining the switch with door-actuated means that when the door is closed the switch is automatically turned off if it has not been turned oif manually before the door is closed, the arrangement being such however that if the switch has been turned ofi' before the door is closed, the door-ac tuated controlling means will not operate to throw the switch from open to closed position.

rihis and other features of the invention will be particularly described in the following specification and will be defined in the claims hereto annexed.

In the accompanying drawings I have illustrated a simple and convenient form of device for carrying into eect the principles of this invention, in which:

Figure 1 is a side elevation of the complete device arranged in proximity to a door which is shown in section.

Figure 2 is a plan view of the same device, a door and wall being partly shown in section.

Figure 3 is a horizontal central section showing the operative means by which the door-actuated lever actuates the switch mechanism.

Figures 4 and 5 are perspective views showing, res ectively, two ratchet members included in t switch actuating mechanism..

Figure 6 is an end elevation showing the tyo ratchet members in operative relations 1p.

Figure 7 is a detail view of thelower end of the door-actuated arm illustrating how the pull member or cord is adjustably connected with said arm.

In. carrying out the principles of this inventlon I employd any ordinary type of wall switch oplerated by a rotatable spindle through t e medium of a button or other equivalent gripping means at its outer end. As the precise construction of the wall switch proper forms no part of this invention I lave illustrated the principal parts of said switch which are pertinent to this invention without attempting to show all details thereof.

The type of switch illustrated in the drawings comprises a hollow porcelain body member 1, carrying a rotatable spindle 2, by whose rotation the diametrically projecting switch arms 3 are thrown by successive turns, through say a quarter of an are, into and out of circuit-closing engagement with the electrical terminals one of which is shown at 4. The gripping button or member 3a secured to the outer or front end of the spindle permits the switch to be readily operated by hand. A casing or lid 13 serves to cover the working parts and is provided with an opening or window 13 to expose to view the indicator plate on the spindle to show whether the switch is closed or open.

The essence 0f the invention consists`v generally speaking, in combining with a switch of such a type or its equivalent, a ratchet pull mechanism which is so connected or co-ordinated with an actuating arm located to be operated by the door cominginto closed posit-ion so as to throw the switch from closed to open position but to fail to throw the switch to closed position when it is already open.

The specific mechanism shown for accomplishing this purpose embraces a stud member 7 projected from a supporting plate 7a and at its outer end provided with a bearing recess to receive the rear end of the switch spindle 2. An annular or recessed base member 6 is secured to the wall and to the forward face of this base member or support. The switch itself is detachably secured in any suitable manner with the rear end of the switch spindle 2 properly pro,

' jecting sli htlgf into the bearin recess position as indicated in Fi res `4 and. 6,

formed in t e ront end of the stu 7.

On the rearI end of the spindle next to this bearing is secured one ratchet member cornprising a disk or plate 14 havmg diametricall opposed peripheral ratchet teeth or cam` su aces 15 each formed with a gradual slo e and terminating in an abrupt shoulder.

n the stud 7 is mounted the other ratchet member which comprises a centrally perforated disk or pulley 8, with its periphery grooved to retain a flexible pull member, which in this case is in the form of the usual pull chain 9- one end of which 1s anchored to the pulley and the other end of which passes out through an openlng 1'n the base for adjustable attachment to the plvotal arm 22. A torsion spring 11 is coiled around the stud with one end projecting out to engage or hook against a stop p1n 12 on the plate 7, while the other end of said torsion spring is bent around a rearwardly projecting pin 10 attached to the rear face of the ratchet pulley 8. To the front face of the pulley is secured the ratchet member comprising a plate 16 with diametrically projected inclined teeth or prongs 17 so arranged as to ride over the sloping faces of the cam teeth 15 on ratchet plates 14, when rotated in a contraloclgwise direction as indicated by the arrow 1n Figure 4 b the tension of the torsion spring 11.

n the door-post ledge immed1ately adjacent to the swinging edge of the door 30 is mounted a. plate 20 which carries a screw 21 which serves as a fulcrum for the lever or arm 22 whose upper end may be provided with a roller or knob 23 to be engaged by the door and pushed inwardly as the. door closes. The pull or chain member 9 1s attached to the lower end of said lever and preferably in such a way as to provlde for adjustment -to secure the proper act-lon. In this case, as a chain is used the arm 1s provided with a series of shallow transverse sockets for receiving a series of several adjacent bolts of the chain which are held in lace by means of overhanglng screw 24.

he lower end of the lever is pro-vided with a shoulder 26, and adjacent thereto is pivoted a latch 27 in position to be hooked against said shoulder and to drop away therefrom when the tension is released. The upper attaching screws of the plate 20 may serve to limit the are of movement of the arm 22 in either direction or the latch itself may serve as one of these arm-limiting stops.

The operation of the device is as follows. When the doo-r is open the arm 22, under the tension of the pull member 9, caused by the torsion spring 11, will tend to assume a position shown in dotted lines in Figure 1. In this position the diametric ratchet teeth 17, let us assume, lie in the vertical while the co-operating rat'c et member if the lights are on, that is if the switch is closed, is at rest with the diametrical axis of its ratchet teeth 15 extending in a horizontal'direction as indicated in Figure 5. It should be noted that the torsion spring not only imparts a torsional movement in a contraclockwise direction to the driving member of the ratchet couple to wind u the pull chain, but it also exerts an outwar pressure on said driving member of the ratchet couple to press it yieldingly into engagement with the driven member 14 of the ratchet con le. Now with the parts in the position in icated in Figures 4 and 5, the teeth 17 lie between the two co-operating teeth l15 with the two plates pressed into close contact so that a rotation through a small arc brings the abrupt edges of teeth 17 against the abrupt shoulder of teeth 15, after which a continued rotation of the driving' member 16 under the pull of the chain 9, serves to rotate the driven member 14 secured to the switch spindle thro ha suiiicient arc, perhaps 90 or more, to t row the switch beyond its dead center, thereby shifting the switch from closed to open position.

Suppose, however, that the switch is already in open position in which case the teeth 15 will be in vertical relationship as shown in full lines in. Figure 6. In such case the teeth 17 will have to travel through an arc several times as great as in the former case before operative engagement is established between said teeth 17 to operatively engage the shoulders of teeth 15. Now the device is adjusted in this particular case so that the movement of the actuating arm 22, from its limit when the door is open to its inward limit when the door is closed, produces a rotation of approximately half the circumference of the driv.

ing ratchet member, and so much of this entire .are of rotation is consumed rin lost motion before operative engagement is established between the teeth 17 and the teeth 15 when the switch is closed or on, that insufficient rotation of the spindle is pro-` duced to turn the switch to or beyond its dead center. In such case, therefore, there is a small rotative movement of the switch spindle through the two engaged ratchet members which, however, does not result in throwing the switch. This differential rotation of the switch spindle, according to the initial position of the switch itself whether in off or on position, is vital to the pro er functioning of the device.

ases may arise where one may wish to leave the cellar door open while inside the cellar and desires to avoid having the light turned off by the closing of the door accidentally or otherwise.- In such case, after the door is open the latch 27 is thrown into engagement with the arm 22 which is shoved to proper position for that purpose and the friction induced by the tension of the pull member 9 serves to keep these parts interlocked. It the door is closed, in such case the driving ratchet member will not have been rotated sniciently to lie in position to throw the switch after the switch has been turned on by hand and, consequently, does not tlnow the switch. Such closing of the door, however, will release the latch member so that when the door is next opened the arm is free to allow the driving ratchet member to return to its normal initial position and function properly on the next closing of the door.

It will be seen that there is no interference whatever with the manual operation of the switch whether the door be open or closed yet on leaving the room containing the switch the lights will'be automatically cut olf by the closing door, in case of oversight, while the open switch will not be closed by the door in any case. The device may be temporaril held against action for a single occasion and thereafter restores itself to normal operation by one closing of the door or the connection between the lexible pull and the actuating arm may be released by slaclrening the ret'aining screw 24, which connection however may be readily restored by again at taching the pull chain.

Vhat I claim is:

1. A safety switch device embracing in combination, a snap switch of the intermittently rotatable spindle type including an insulating base, a hollow supporting member upon which said base is mounted, a rotatable chain drum mounted next said supporting member and having ratchet connection with the switch spindle to throw the switch, and 'a return spring for rewinding the chain on the drum, and a .chain-pulling lever pivotally mounted in juxtaposition to the door to be actuated by the pressure of the door to pull the chain and actuate the switch one step when the door is closed, substantially as described.

2. A safety switch device embracing in combination a snap switch of the intermittently rotatable spindle type having at its outer end a manual operating device and at its other end a ratchet-pull actuating member, a pivotal lever connected with said chain mounted to be actuated by engagement with the door when the same is closed to pull the ch'ain and actuate the switch, and manually controlled means for locking the lever against moving in the reverse direction, substantially as described. 3. A safety switch device embracing in combination a switch-actuating lever pivotally mounted on the doorframe to be engaged and moved in switch-actuating direction by the closing door, a rotatable snap switch provided with a ratchet-pull chain connected to the opposite end of said levery to that engaged by the door, a gravity latch adapted to be moved by hand into engagement with said lever to prevent its reverse movement when the door is opened and to be disengaged by gravity the next time the door is closed, substantially as described.

4. In a safety switch the combination with a manually operable rotatable snap switch, of a ratchet pull device operatively connected with said switch to give it diiferent arcs of rotation dependent upon the switch being in open or closed position, a pivoted arm located adjacent to a door to be actuated by the closing of the door combined with said ratchet pull to rotate the switch through the larger arc when the switch is in closed position and in the smaller arc when the switch is open, and means for temporarily preventing the arm from performing its normal operation by the closingr of the door, substantially as described.

In witness whereof, I have subscribed the above specification.

ERNEST H. THOMPSON 

